With the repaid development of the semiconductor technology, the integration level of the ultra large-integration (ULI) has been progressed into a scale with millions and billions devices in a chip; and the multiple-layer metal interconnect technique which utilizes two or more layers of metal interconnect structures has been widely used. Currently, the conventional metal interconnect structures are made of aluminum. However, with the continuous decreasing of the feature size of the semiconductor devices in the integrated circuits, the circuit density of the metal interconnect lines has been continuously increased, the required response time has been continuously decreased. Thus, the conventional aluminum interconnect lines are often unable to match the requirements.
When the feature size of the semiconductor devices enters into a scale of 130 nm or below, the Cu interconnect technique has been used to substitute the convention Al interconnect technique. However, when the feature size of the semiconductor device is further miniaturized, the electrical current carried by the interconnect lines has become larger and larger, and it has almost reached the limitation of the Cu interconnect lines. Further, the surface scattering and the crystal boundary scattering of the Cu interconnect lines have become more and more intense; and the resistance of the Cu interconnect lines is increased. Thus, the reliability of the Cu interconnect structures is reduced. Therefore, it may need to look for a novel material to substitute Cu to increase the reliability of the metal interconnect structures.
Carbon nanotubes have a plurality of advantages, and they are well proved to be the novel interconnect material to substitute the Cu interconnect structures. Carbon nanotubes have a significantly high thermal conductivity. Thus, they favor the dissipation of heat. Further, the transport mode of the carriers in a carbon nanotube is a ballistic transport mode, the transport of the carriers in the carbon nanotube may barely be affected by the scattering effect. Thus, carbon nanotubes may carry a significantly large current density. Further, carbon nanotubes also have a significantly large mechanical strength and thermal stability, and a substantially low power consumption, etc.
It may be difficult to form carbon nanotubes along a lateral direction, thus the carbon nanotubes used as a part of an interconnect structure are commonly grown in a vertical through hole. However, the reliability of the interconnect structures using carbon nanotubes needs further improvements. The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems